This invention relates to a precleaner assembly for the air intake system of a heavy duty vehicle.
In order to assure satisfactory life of the vehicle air cleaner cartridge, it is necessary, particularly in heavy duty vehicles operated in dusty or dirty environments, to separate heavier particles from the incoming air stream before the latter is communicated to the air filter. Prior art precleaner assemblies have accomplished this separation of the heavier dust or dirt particles by providing a fin ring or turning vanes to induce spiral or vortex flow components into the incoming air stream. Movement of the dust particles in the spiral path generates centrifugal forces which urge the latter radially outwardly with respect to the flow stream, so that these particles are concentrated in the radial outermost portions thereof. This portion is then ejected, and the remaining portion of the flow stream saved for communication to the engine. However, the efficiency of precleaner assemblies of this type is dependent upon the pressure drop across the fin ring located within the structure and carrying the turning vanes. Prior art devices were dependent upon engine intake manifold vacuum to induce air flow through the vanes. However, performance of this type of air cleaner is marginal at best, because the relatively low pressure differential across the vanes induces a very weak vortex flow of the fluid, thus inhibiting proper separation of the dust particles.
The present invention increases the efficiency of the precleaner assembly by taking advantage of the ram air effect caused by the moving vehicle to increase the pressure level of the incoming air flow. Then, as the air flow moves across the fin ring carrying the turning vanes, the diameter of the precleaner housing increases, to thereby increase the flow area and to rapidly decrease the pressure level of the incoming fluid. These two factors combine to greatly increase the pressure drop across the turning vanes, thereby causing the latter to induce a much stronger vortex than was possible in prior art devices. The stronger vortex or spiral flow action increases the centrifugal forces tending to urge the dust particles radially outwardly with respect to the flow path, thus concentrating a large percentage of the particles in the radial outwardmost portion of the flow stream, which is ejected from the housing.